In recent years, the amount of data used by information terminals, the Internet, and cloud services has increased explosively. In accordance with this, memory devices are required to have increased capacity and reduce the bit cost.
An ideal memory device is a nonvolatile semiconductor device operating at high speed, having a high storage density, and having a reduced bit cost. Under the circumstances, however, there is no memory device that satisfies all these requirements, and a memory device suited for a particular purpose is provided to the user.